The present invention relates to fabrics made from poly(vinyl alcohol) fibers, that are at least partially saturated with a solvent, and useful as wipes.
Wipes are used for many purposes in a variety of applications. When saturated with solvents, wipes provide a convenient method of cleaning surfaces. However, wipes of the prior art suffer from a number of drawbacks. For example, many fabrics used for wipes are not sufficiently absorbent, and do not hold or distribute the solvent very well. Many materials used for the fabrics are not very resistant to acids and bases, or degrade when stored for intermediate periods of time. Other fabrics, such as cellulose-based fabrics, are not very strong, and fall apart when contacted with solvent. Thus, there is a need for a wipe with improved absorbency, shelf life, chemical resistance, and strength.
It has been discovered that wipes constructed of poly(vinyl alcohol) give improved absorbency, shelf life, chemical resistance, and strength over wipes of the prior art. Thus, in one aspect the invention provides a fabric comprising poly(vinyl alcohol) fibers, and a solvent, wherein the fabric is at least partially saturated with the solvent.
In another aspect the invention provides a kit comprising a container, and a plurality of adjacent sheets disposed within the container, wherein the sheets comprise the fabric.
In another aspect the invention provides a kit comprising a container; and a roll of the fabric disposed within the container; wherein the fabric comprises a width and a length, the length/width ratio is greater than 10:1, a series of perforations traverse the width of the fabric at evenly spaced intervals.
In still another aspect the invention provides a method of using the fabric comprising contacting the fabric with the residue of a chemical process or mechanical process.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The present invention may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the Examples included therein.
Before the present materials and methods are disclosed and described, it is to be understood that this invention is not limited to specific methods or materials as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
Use of Terms
As used in the specification and the appended claims, the singular forms xe2x80x9ca,xe2x80x9d xe2x80x9canxe2x80x9d and xe2x80x9cthexe2x80x9d include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to xe2x80x9ca fiberxe2x80x9d includes mixtures of fibers.
Ranges are often expressed herein as from xe2x80x9caboutxe2x80x9d one particular value, and/or to xe2x80x9caboutxe2x80x9d another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent xe2x80x9cabout,xe2x80x9d it will be understood that the particular value forms another embodiment. Similarly, when ranges extend from one endpoint to another endpoint, another embodiment includes the range between the endpoints and excluding the endpoints.
References in the specification and concluding claims to parts by weight, of a particular element or component in a composition or article, denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound.
A weight percent of a component, unless specifically stated to the contrary, is based on the total weight of the formulation, composition, or material in which the component is included.
A residue of a chemical process, as used in the specification and concluding claims, refers to the resulting product or by-product of a particular reaction scheme or chemical process. A residue of a mechanical process refers to the by-product or waste generated during the mechanical process, such as grease, grime, or particulate matter.
By the term xe2x80x9ceffective amountxe2x80x9d of a compound or property as provided herein is meant such amount as is capable of performing the function of the compound or property for which an effective amount is expressed. As will be pointed out below, the exact amount required will vary from process to process, depending on recognized variables such as the compounds employed and the processing conditions observed. Thus, it is not always possible to specify an exact xe2x80x9ceffective amount.xe2x80x9d However, an appropriate effective amount may be determined by one of ordinary skill in the art using only routine experimentation.
Degree of hydrolysis also includes degree of saponification where saponification is employed in the preparation of poly(vinyl alcohol).
Solvent means any liquid which is suitable for use in a wipe, and includes pure liquids, mixtures of liquids, and solutions that contain dissolved ingredients such as softeners and cleaning agents.
In one aspect the invention provides a fabric comprising poly(vinyl alcohol) fibers, and a solvent, wherein the fabric is at least partially saturated with the solvent.
In another aspect the invention provides a kit comprising a container, and a plurality of adjacent sheets disposed within the container, wherein the sheets comprise the fabric.
In another aspect the invention provides a kit comprising a container; and a roll of the fabric disposed within the container; wherein the fabric comprises a width and a length, the length/width ratio is greater than 10:1, a series of perforations traverse the width of the fabric at evenly spaced intervals.
In still another aspect the invention provides a method of using the fabric comprising contacting the fabric with the residue of a chemical or mechanical process.
The invention is preferably practiced with poly(vinyl alcohol) fibers meeting the following characteristics:
1. Degree of polymerization of poly(vinyl alcohol): Preferably from about 300 to about 5000, more preferably from about 800 to about 3000, and still more preferably from about 1200 to about 2000.
2. Degree of hydrolysis of poly(vinyl alcohol): Preferably greater than 95%, more preferably greater than 97%, even more preferably greater than 98%, even further preferably greater than 99%. In a separate embodiment, when the solvent is not water, the degree of hydrolysis can be as low as 80% and below 85%, 90%, or 95%.
3. Average denier of fibers: Preferably from about 0.1 to about 10, more preferably from about 0.5 and about 5, and even more preferably from about 1 to about 3 denier.
4. Average length of fibers: Preferably from about 4 mm to about 300 mm, more preferably from about 5 to about 100 mm, even more preferably from about 15 to about 60 mm, and most preferably from about 38 mm. The foregoing lengths are preferred when using staple fibers to form nonwoven fabrics. In another embodiment the fibers are continuous filaments. Continuous filaments are especially useful to form woven or knitted fabrics. Continuous filaments are preferably less than about 3 deniers.
5. Temperature above which the fiber is soluble in water, and below which the fiber is insoluble in water, in separate embodiments: 20xc2x0 C., 30xc2x0 C., 40xc2x0 C., 50xc2x0 C., 60xc2x0 C., 70xc2x0 C., 80xc2x0 C., 90xc2x0 C., 100xc2x0 C., and 110xc2x0 C.
The fabric can be made by a number of potential processes, including pressure liquid entangling (i.e. hydroentangling using any suitable liquid). Thus, in one embodiment the fabric is produced by a method comprising the consecutive steps of supporting a plurality of poly(vinyl alcohol) fibers on a mesh screen to form a web; pressure liquid-entangling the web; and drying the web.
The pressure liquid entangling can be performed under any conditions that does not materially affect the desired properties of the web. For hot water soluble poly(vinyl alcohol) the liquid entangling is preferably performed with water.
The pressure liquid entangling is preferably performed at a water pressure of from about 10 to about 200 bar, more preferably at a water pressure of from about 20 to about 120 bar, and even more preferably at a water pressure of from about 40 to about 100 bar. The drying is preferably performed at a temperature of from about 20xc2x0 C. to about 190xc2x0 C., and in an alternative embodiment at a temperature that exceeds the solubility temperature of the poly(vinyl alcohol) in water. The drying is preferably performed by passing heated air through the web. Even more preferably, the web is dried by passing it over a perforated wheel that draws air through the fabric and into the perforated wheel.
The pressure liquid entangling method might also preferably comprise other steps, including, after the first step, the steps of cross-lapping the web; and stretching the web in the machine direction. The method might also comprise, after the drying step, winding the web onto a roll.
Other methods to produce the fabrics of the present invention include heat fusion (which includes thermobonding), chemical bonding, needlepunching, stitchbonding, weaving, and knitting.
The fabric preferably satisfies the following criteria:
1. Thickness: Preferably from about 0.1 mm to about 5 mm, more preferably from about from about 0.3 mm to about 0.6 mm, and most preferably about 0.4 mm.
2. Base weight: Preferably from about 20 g/m2 to about 400 g/m2, more preferably from about 35 to about 200 g/m2, even more preferably from about 50 to about 100 g/m2, still even more preferably from about 60 to about 80 g/m2, and most preferably about 70 g/m2. In an alternative embodiment the preferred base weight is from about 100 to about 200 g/m2, still even more preferably from about 140 to about 160 g/m2, and most preferably about 150 g/m2.
The poly(vinyl alcohol) fabric may also include other fibers selected from the group consisting of polyester, polypropylene, polyethylene, rayon, cellulose, nylon, ethylene/(meth)acrylic acid copolymer, and other fibrous polymers known in the art.
A number of liquids can be used for the solvent, including without limitation water, methyl ethyl ketone, methyl propyl ketone, acetone, isopropyl alcohol, and mixtures thereof. In preferred embodiments the solvent comprises a mixture of water and isopropyl alcohol or a mixture of methyl ethyl ketone and methyl propyl ketone.
In one particular embodiment the solvent comprises from about 35 to about 95 weight parts methyl ethyl ketone, and from about 5 to about 65 weight parts methyl propyl ketone, preferably from about 55 to about 75 weight parts methyl ethyl ketone, and from about 25 to about 45 weight parts methyl propyl ketone. In another particular embodiment the solvent comprises from about 50 to about 98 weight parts isopropyl alcohol, and from about 2 to about 50 weight parts water, preferably from about 75 to about 95 weight parts isopropyl alcohol, and from about 5 to about 25 weight parts water. In still another embodiment the solvent comprises about 1 to about 10 weight parts isopropyl alcohol, and from about 99 to about 90 weight parts water.
An advantageous feature of this wipes of this invention is their ability to absorb, retain, and distribute liquids. Thus, in separate embodiments, the web is capable of absorbing greater than 5, 5.5, 6, 6.5, 7, 7.5, and 8 weight parts solvent per weight part web. When the solvent is water, the web is capable of absorbing greater than 5, 5.5, 6, 6.5, 7, 7.5, and 8 weight parts solvent per weight part web. When the solvent is a mixture of isopropyl alcohol and water, the web is capable of absorbing greater than 5, 5.5, 6, 6.5, 7, 7.5, and 8 weight parts solvent per weight part web. When the solvent is a mixture of methyl ethyl ketone and methyl propyl ketone, the web is capable of absorbing greater than 2.5, 3, 3.5, 4, 4.5, and 5 weight parts solvent per weight part web.
Thus, the web can be saturated with solvent to varying degrees, including, in separate embodiments, greater than 20, 30, 40, 50, 60, 70, 80, and 90 wt.% of maximum absorption. The fabric preferably comprises greater than about 2, 3, 4, 5, 6, 7, or 8 weight parts solvent per weight part web, and/or less than 9, 8, 7, 6, or 5 weight parts solvent per weight part web.
In one embodiment the fabric is configured into a sheet having a width and a length, neither of which is greater than 50 centimeters. In another embodiment the width and length do not exceed 30 centimeters. In still another embodiment the length/width ratio is greater than 10:1, and the fabric is configured into a roll.
An important attribute of the fabrics made by the process of this invention is their superior physical properties. Thus, the fabric preferably satisfies one or more of the following properties, and can satisfy any combination of the following properties.
1. Tensile Strength: The fabric preferably has a tensile strength in the machine direction greater than about 10, 15, or 20 pounds, and/or a tensile strength in the cross direction greater than about 10, 15, or 20 pounds when measured for a one inch strip according to ASTM D5035-95.
2. Bursting Strength: The fabric preferably has a bursting strength greater than 6, 8, or 10 psi when measured by ASTM D3776-96.
Still another advantageous feature of the fabrics of the present invention is their stability in the presence of acids and bases. For example, the fabrics are preferably stable against 50% sodium hydroxide solutions, and 20% sulfuric acid solutions. Thus, the acids and bases can be used as the solvents in the present invention, or the fabrics can be used to wipe acids and bases.